Meng Peij ie，an ordinary girl who was among the 10 people awarded the title of “Touching China 2011”，must be both optimistic and strong-minded. Otherwise, she her disabled adoptive mother for 12 years.
A. mustn't have looked after
B. can't have looked after
C. couldn't have been looking after
D. shouldn't have looked after
网友回答
A. mustn't have looked after
B. can't have looked after
(答案→)C. couldn't have been looking after
D. shouldn't have looked after
解析：本题考查虚拟语气。结合后半句句意“否则，她不可能照顾她残疾的养母12年”可知此处是与过去相反的虚拟语气。